Photoelectric conversion element, photoelectric conversion element assembly and photoelectric conversion module

ABSTRACT

To provide a photoelectric conversion element that allows connection between adjacent photoelectric conversion elements by use of an inexpensive wiring member. 
     A photoelectric conversion element of the present invention comprises: a first semiconductor layer of a first conductivity type; a first electrode arranged on the back side of the first semiconductor layer and electrically connected to the first semiconductor layer; a second semiconductor layer of a second conductivity type, the second semiconductor layer brought into contact with the first semiconductor layer and arranged at least in part on the light-receiving side of the first semiconductor layer; a light-receiving face-side electrode provided so as to be electrically connected to the second semiconductor layer on its light-receiving side; a second electrode arranged on the back side of the first semiconductor layer, and electrically separated from the first semiconductor layer, but electrically connected to the second semiconductor layer; and a penetrating-connecting section penetrating the first semiconductor layer, and electrically separated from the first semiconductor layer, but electrically connecting the light-receiving face-side electrode with the second electrode, wherein the photoelectric conversion element is characterized in that the first electrode and the second electrode are arranged equidistantly apart from a central axis passing through a center of the photoelectric conversion element.

This application is the U.S. national phase of International ApplicationNo. PCT/JP2008/063421 filed 25 Jul. 2008 which designated the U.S. andclaims priority to Japan Application No. 2007-226328 filed 31 Aug. 2007,the entire contents of each of which are hereby incorporated byreference.

TECHNICAL FIELD

The present invention relates to a photoelectric conversion element, aphotoelectric conversion element assembly, and a photoelectricconversion module.

BACKGROUND ART

In recent years, expectations for photoelectric conversion elements thatdirectly convert sunlight energy into electric energy have been rapidlyincreased as a next generation of energy sources particularly from theviewpoint of environmental issues. Currently mainstream photoelectricconversion elements use silicon crystals.

Among them, an MWT (Metallization Wrap Through) photoelectric conversionelement has been proposed in order to decrease the area occupation rateof a surface electrode and inhibit carrier recombination in an areabelow the surface electrode (Non-Patent Document 1). This MWTphotoelectric conversion element has a structure in which a part of thesurface electrode is arranged on the back side via a through-hole formedin a silicon substrate to allow decrease of the area occupation rate ofthe surface electrode.

A p-side electrode at a back side of one MWT photoelectric conversionelement is connected with an n-side electrode at a back side of anadjacent MWT photoelectric conversion element by use of aninterconnection foil to form a photoelectric conversion element assembly(Non-Patent Document 2). The interconnection foil has a patternedaluminum layer, and a surface of one part where the aluminum layer iselectrically connected to each electrode at the back side of the MWTphotoelectric conversion element is worked up so that an anti-corrosionlayer is formed thereon, and the other part is coated with an isolatingvarnish. Conduction between each electrode at the back side of the MWTphotoelectric conversion element and the anti-corrosion layer is madevia a conductive adhesive.

Non-Patent Document 1: “A SYSTEMATIC APPROACH TO REDUCE PROCESS-INDUCEDSHUNTS IN BACK-CONTACTED MC-SI SOLAR CELLS”, IEEE 4th World Conferenceon Photovoltaic Energy Conversion, U.S.A., 2006, pages 1319-1322, FilipGranek et al.

Non-Patent Document 2: “SINGLE-STEP LAMINATED FULL-SIZE PV MODULES MADEWITH BACK-CONTACTED MC-SI CELLS AND CONDUCTIVE ADHESIVES”, 19th EuropeanPhotovoltaic Solar Energy Conference, France, 2004, pages 2145-2148, P.C. de Jong et al.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

Since the interconnection foil has complicated patterning, it isnecessary to arrange the photoelectric conversion element on theinterconnection foil with a high positioning accuracy in order to avoidtrouble such as defective connection between the interconnection foiland the MWT photoelectric conversion element. Furthermore, theconductive adhesive and the production process of the interconnectionfoil cost more than an inter-connector.

In view of such circumstances, the present invention has been achievedto provide a photoelectric conversion element that allows connectionbetween adjacent photoelectric conversion elements by use of aninexpensive wiring member.

Means for Solving the Problems and Effects of the Invention

A photoelectric conversion element of the present invention comprises: afirst semiconductor layer of a first conductivity type; a firstelectrode arranged on the back side of the first semiconductor layer andelectrically connected to the first semiconductor layer; a secondsemiconductor layer of a second conductivity type, the secondsemiconductor layer brought into contact with the first semiconductorlayer and arranged at least in part on the light-receiving side of thefirst semiconductor layer; a light-receiving face-side electrodeprovided so as to be electrically connected to the second semiconductorlayer on its light-receiving side; a second electrode arranged on theback side of the first semiconductor layer, and electrically separatedfrom the first semiconductor layer, but electrically connected to thesecond semiconductor layer; and a penetrating-connecting sectionpenetrating the first semiconductor layer, and electrically separatedfrom the first semiconductor layer, but electrically connecting thelight-receiving face-side electrode with the second electrode, whereinthe photoelectric conversion element is characterized in that the firstelectrode and the second electrode are arranged equidistantly apart froma central axis passing through a center of the photoelectric conversionelement.

In the present invention, the first electrode and the second electrodeare arranged equidistantly apart from the central axis passing throughthe center of the photoelectric conversion element. Therefore, when twophotoelectric conversion elements are arranged side by side andelectrically connected to each other, and one photoelectric conversionelement is turned around an axis perpendicular to the principal surfaceby 180 degrees, and then the central axes of each element are arrangedon the same straight line, the first electrode of one photoelectricconversion element and the second electrode of the other photoelectricconversion element will necessarily be positioned on a straight lineparallel to the central axes. Accordingly, the first electrode of onephotoelectric conversion element and the second electrode of the otherphotoelectric conversion element can be connected by use of a linearinter-element wiring member. Since two photoelectric conversion elementscan be connected by use of a linear inter-element wiring memberaccording to the present invention, the period of time for this wiringprocess can be shortened. In addition, linear inter-element wiringmembers are relatively inexpensive, and therefore production costs canbe reduced.

Hereinafter, various embodiments of the present invention will beexemplified.

The second electrode may have an asymmetrical shape with respect to thecenter point of the penetrating-connecting section.

A distance between the first electrode and the central axis, and adistance between the penetrating-connecting section and the central axismay be different from each other.

The second electrode may be plural, the plural second electrodes beingarranged along a direction parallel to the central axis.

The first electrode may be plural, the plural first electrodes beingarranged along a direction parallel to the central axis.

There may be pairs of electrodes, each pair consisting of the firstelectrode and the second electrode arranged equidistantly apart from thecentral axis.

The present invention also provides a photoelectric conversion elementassembly comprising: a first photoelectric conversion element; and asecond photoelectric conversion element, each of which comprises: afirst semiconductor layer of a first conductivity type; a firstelectrode arranged on the back side of the first semiconductor layer andelectrically connected to the first semiconductor layer; a secondsemiconductor layer of a second conductivity type, the secondsemiconductor layer brought into contact with the first semiconductorlayer and arranged at least in part on the light-receiving side of thefirst semiconductor layer; a light-receiving face-side electrodeprovided so as to be electrically connected to the second semiconductorlayer on its light-receiving side; a second electrode arranged on theback side of the first semiconductor layer, and electrically separatedfrom the first semiconductor layer, but electrically connected to thesecond semiconductor layer; and a penetrating-connecting sectionpenetrating the first semiconductor layer, and electrically separatedfrom the first semiconductor layer, but electrically connecting thelight-receiving face-side electrode with the second electrode, whereinthe first electrode of one photoelectric conversion element and thesecond electrode of another photoelectric conversion element areelectrically connected by use of a linear inter-element wiring member.

The present invention also provides a photoelectric conversion elementassembly comprising: a first photoelectric conversion element and asecond photoelectric conversion element, wherein each of the first andsecond photoelectric conversion elements is the above-describedphotoelectric conversion element, the central axes of the first andsecond photoelectric conversion elements are arranged on the samestraight line, and the first electrode of one photoelectric conversionelement and the second electrode of the other photoelectric conversionelement are arranged so as to be positioned on a straight line parallelto the central axes, and the first electrode of one photoelectricconversion element and the second electrode of the other photoelectricconversion element are electrically connected by use of a linearinter-element wiring member.

The second electrode may have an asymmetrical shape with respect to thecenter point of the penetrating-connecting section.

In each photoelectric conversion element, a distance between the firstelectrode and the central axis, and a distance between thepenetrating-connecting section and the central axis may be differentfrom each other.

The present invention also provides a photoelectric conversion modulecomprising the above-described photoelectric conversion elementassembly.

The various embodiments shown herein may be combined with one another.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1( a) and 1(b) are a plan view (figure of a light-receivingsurface) and a back view, respectively, illustrating a configuration ofa photoelectric conversion element in accordance with a first embodimentof the present invention.

FIG. 2 is a sectional view of the photoelectric conversion element takenalong the chain line I-I of FIG. 1( b).

FIGS. 3( a) to 3(d) are sectional views illustrating production steps ofthe photoelectric conversion element in accordance with the firstembodiment of the present invention.

FIGS. 4( e) to 4(g) are sectional views illustrating production steps ofthe photoelectric conversion element in accordance with the firstembodiment of the present invention.

FIG. 5 is a back view illustrating a configuration of a photoelectricconversion element assembly in accordance with the first embodiment ofthe present invention, corresponding to the photoelectric conversionelement shown in FIG. 1( b).

FIGS. 6( a) and 6(b) are a plan view (figure of a light-receivingsurface) and a back view, respectively, illustrating a configuration ofa photoelectric conversion element in accordance with a secondembodiment of the present invention.

FIG. 7 is a back view illustrating a configuration of a photoelectricconversion element assembly in accordance with the second embodiment ofthe present invention, corresponding to the photoelectric conversionelement shown in FIG. 6( b).

FIG. 8 is a view illustrating a configuration of a photoelectricconversion element assembly in accordance with a third embodiment of thepresent invention as seen from a back side of a photoelectric conversionelement.

DESCRIPTION OF THE REFERENCE NUMERALS

-   1 First semiconductor layer (p-type layer)-   2 First electrode-   3 Second semiconductor layer (n-type layer)-   5 Light-receiving face-side electrode-   5 a Base part of light-receiving face-side electrode-   5 b Branch part of light-receiving face-side electrode-   5 c Wide part of light-receiving face-side electrode-   7 Second electrode-   9 Penetrating-connecting section-   9 a Through-hole-   10 Photoelectric conversion element-   10 a First photoelectric conversion element-   10 b Second photoelectric conversion element-   11 Central axis-   13 Aluminum electrode-   15 High-concentration p-type layer-   17 Inter-element wiring member-   19 Separation band-   21 Junction isolation section-   23 Antireflection film-   25 P-type semiconductor substrate

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, various embodiments of the present invention will bedescribed with reference to the drawings. The contents shown in thedrawings and the following description are exemplification, and thescope of the present invention is not limited to the contents shown inthe drawings and the following description. Hereinafter, the descriptionwill be provided taking the case where the first conductivity type isp-type as an example. In addition, reading of the following descriptionwhile replacing “p-type” with “n-type” as necessary will allow thefollowing description to be basically applicable to the case where thefirst conductivity type is n-type.

1. First Embodiment 1-1. Configuration of Photoelectric ConversionElement

First, the configuration of the photoelectric conversion element inaccordance with the first embodiment of the present invention will bedescribed with reference to FIGS. 1( a) and 1(b), and FIG. 2. FIGS. 1(a) and 1(b) are a plan view (figure of a light-receiving surface) and aback view, respectively, illustrating the configuration of thephotoelectric conversion element in accordance with this embodiment; andFIG. 2 is a sectional view of the photoelectric conversion element takenalong the chain line I-I of FIG. 1( b).

A photoelectric conversion element 10 of this embodiment comprises: ap-type first semiconductor layer 1 (hereinafter, referred to as “p-typelayer”); a first electrode 2 arranged on the back side of the p-typelayer 1 and electrically connected to the p-type layer 1; an n-typesecond semiconductor layer 3 (hereinafter, referred to as “n-typelayer”) brought into contact with the p-type layer 1 and arranged atleast in part on the light-receiving side of the p-type layer 1; alight-receiving face-side electrode 5 provided so as to be electricallyconnected to the n-type layer 3 on the light-receiving side of then-type layer 3; a second electrode 7 arranged on the back side of thep-type layer 1, and electrically separated from the p-type layer 1, butelectrically connected to the n-type layer 3; and apenetrating-connecting section 9 penetrating the p-type layer 1, andelectrically separated from the p-type layer 1, but electricallyconnecting the light-receiving face-side electrode 5 with the secondelectrode 7.

The first electrode 2 and the second electrode 7 are arrangedequidistantly apart from a central axis 11 passing through a center ofthe photoelectric conversion element 10. The central axis 11 is parallelto a principal surface of the photoelectric conversion element 10. Thecentral axis 11 divides the photoelectric conversion element 10 into twopieces of the same shape in a plan view. When the planar shape of thephotoelectric conversion element 10 is a square or a rectangle, thecentral axis 11 is a straight line that passes through the center of thesquare or the rectangle and is parallel to one side of the square, or ashorter side or a longer side of the rectangle. The central axis 11 isparallel to a direction in which a plurality of photoelectric conversionelements 10 are arranged to be connected in series.

An aluminum electrode 13 is arranged at the back side of the p-typelayer 1. A high-concentration p-type layer 15 in which a highconcentration of p-type impurities are doped is formed immediately underthe aluminum electrode 13. The first electrode 2 and the secondelectrode 7 are independently used for connection to differentinter-element wiring members 17 (see FIG. 5). A separation band 19 isprovided so as to have a circular shape between the second electrode 7and the aluminum electrode 13. Thereby, the second electrode 7 and thealuminum electrode 13 are insulated. The separation band 19 is providedwith a junction isolation section 21 in a circular shape. Thereby, thep-type layer 1 and the n-type layer 3 are insulated securely. Anantireflection film 23 is provided at the light-receiving side of then-type layer 3.

There are provided a plurality of first electrodes 2 and secondelectrodes 7. The plurality of first electrodes 2 are arranged along adirection parallel to the central axis 11, and so are the plurality ofsecond electrodes 7. A first electrode array consisting of a pluralityof first electrodes 2 arranged linearly and a second electrode arrayconsisting of a plurality of second electrodes 7 arranged linearly arein a line-symmetric position with respect to the central axis 11.Instead of arranging the plurality of first electrodes 2 along thedirection parallel to the central axis 11, a first electrode 2 having anelongated shape may be arranged so that a longer direction thereof isparallel to the central axis 11. Arrangement of the plurality of firstelectrodes 2 in a discrete manner brings advantages that the amount ofelectrode materials to be used can be reduced and that stress to bereceived from the inter-element wiring member 17 can be reduced. Thenumber of first electrodes 2 and second electrodes 7 may be one,respectively, but the power generated in the photoelectric conversionelement 10 can be collected efficiently by arranging a plurality ofelectrodes in a distributed manner.

There are provided a plurality of (four, specifically) pairs ofelectrodes, each pair consisting of the first electrode 2 and the secondelectrode 7 arranged equidistantly apart from the central axis 11. Asillustrated in FIG. 1 (b), the distance between the central axis 11 andthe first electrode 2 or the second electrode 7 in the first to fourthpairs are A, B, C, D, respectively. The number of the pairs may be one,but the power generated in the photoelectric conversion element 10 canbe collected efficiently by providing a plurality of pairs that aredifferent from each other in distance from the central axis 11.

The light-receiving face-side electrode 5 is composed of a base part 5 aand a branch part 5 b that is electrically connected to the base part 5a and has a width narrower than that of the base part 5 a. The width ofthe base part 5 a is constant. The penetrating-connecting section 9 isconnected to the base part 5 a.

1-2. Method for Producing Photoelectric Conversion Element

Next, an example of the method for producing the photoelectricconversion element 10 will be described with reference to FIGS. 3( a) to3(d) and FIGS. 4( e) to 4(g).

(1) Step of Forming Through-Hole and Surface Roughening

First, a through-hole 9 a is formed in a p-type semiconductor substrate25 as illustrated in FIG. 3( a). The kind of the substrate 25 is notparticularly limited, and examples thereof include a crystalline siliconsubstrate. The method for forming the through-hole 9 a is notparticularly limited. The through-hole 9 a can be formed by laser beammachining, for example. The shape and dimension of the through-hole 9 aare not particularly limited. Examples of the shape of the through-hole9 a include a quadrilateral (for example, square, rectangle) and acircle.

Next, a roughened structure (textured structure) is formed in thesurface of the substrate 25 by etching the surface with an acid oralkaline solution, or reactive plasma.

(2) Step of Forming N-Type Layer

Next, the n-type layer 3 is formed by introducing n-type impurities tothe substrate 25 as illustrated in FIG. 3( b) to obtain the structureillustrated in FIG. 3( b).

The introduction of n-type impurities can be performed by leaving thesubstrate 25 in a high-temperature gas including a material containingn-type impurities (for example, POCl₃), for example. Through this step,the n-type layer 3 is formed at a top side of the substrate 25, on aside wall of the through-hole 9 a, and at a back side of the substrate25. The remaining part in the substrate 25 that is not the n-type layer3 is the p-type layer 1.

The method for forming the n-type layer 3 is not limited to the methoddescribed herein. The n-type layer 3 may be formed by implanting n-typeimpurity ions into the substrate 25, for example. In addition, then-type layer 3 may be formed by separately forming an n-typesemiconductor layer on the substrate 25 by a CVD method or the like,instead of forming the n-type layer 3 by introducing n-type impuritiesinto the substrate 25. In this case, the substrate 25 itself is thep-type layer 1.

The n-type layer 3 should be arranged at least in part on thelight-receiving side of the p-type layer 1. Therefore, the n-type layer3 arranged on the back side of the p-type layer 1 may be left as is ormay be removed by etching or the like. Or, formation of the n-type layer3 on the back side of the p-type layer 1 may be prevented by introducingn-type impurities into the substrate 25 with the use of a diffusionpreventing mask previously placed on the back side of the substrate 25.

(3) Step of Forming Antireflection Film

Next, the antireflection film 23 is formed on the light-receiving sideof the n-type layer 3 as illustrated in FIG. 3( c).

The antireflection film 23 can be formed on the light-receiving side ofthe n-type layer 3 so as to have an opening in a region where thelight-receiving face-side electrode 5 is to be formed. Theantireflection film 23 may be formed on the whole light-receivingsurface of the n-type layer 3. In this case, the light-receivingface-side electrode 5 is formed on the antireflection film 23, andconduction between the light-receiving face-side electrode 5 and then-type layer 3 can be made by fire-through. The material, thickness,production method, and the like of the antireflection film 23 are notparticularly limited, as long as the film has a function of preventingsurface reflection. The antireflection film 23 is made of an SiN filmhaving a thickness of 70 nm, for example. The antireflection film 23 canbe formed by a plasma CVD method, for example.

(4) Step of Forming Aluminum Electrode and High-Concentration P-TypeLayer

Next, the aluminum electrode 13 is formed on the back side of the p-typelayer 1 as illustrated in FIG. 3 (d). The aluminum electrode 13 can beformed by printing and baking a paste material containing aluminum. Onthis occasion, aluminum diffuses immediately under the aluminumelectrode 13 to form the high-concentration p-type layer 15 (see FIG. 4(e)). The aluminum electrode 13 is formed so as to avoid an area aroundthe through-hole 9 a (area where the second electrode 7 and theseparation band 19 are to be formed in a following step).

(5) Step of Forming First Electrode, Second Electrode, andPenetrating-Connecting Section

Next, as illustrated in FIG. 4 (e), the first electrode 2 and the secondelectrode 7 are formed on the back side of the p-type layer 1, and thepenetrating-connecting section 9 is formed in the through-hole 9 a. Thesecond electrode 7 is formed so as to allow the separation band 19 to beprovided between the second electrode 7 and the aluminum electrode 13.The materials, thicknesses, production methods, and the like of thefirst electrode 2, the second electrode 7, and thepenetrating-connecting section 9 are not particularly limited. Thematerials thereof may be the same or different from one another. Thefirst electrode 2, the second electrode 7, and thepenetrating-connecting section 9 are preferably formed of a metalsuitable for soldering, for example, silver.

The first electrode 2, the second electrode 7, and thepenetrating-connecting section 9 can be formed by a vapor depositionmethod, a printing and baking method with a paste electrode, a platingmethod, or the like. The second electrode 7 and thepenetrating-connecting section 9 can be formed at the same time by amethod in which a conductive paste is printed and baked from the backside, for example. The second electrode 7 and the penetrating-connectingsection 9 can be formed at the same time also by a vapor depositionmethod or a plating method.

(6) Step of Forming Light-Receiving Face-Side Electrode

Next, the light-receiving face-side electrode 5 is formed on thelight-receiving side of the n-type layer 3 as illustrated in FIG. 4 (f).The shape and material of the light-receiving face-side electrode 5 arenot particularly limited, as long as the light-receiving face-sideelectrode 5 is allowed to be electrically connected to the n-type layer3 and collect the power generated from the n-type layer 3 in thephotoelectric conversion element 10. The light-receiving face-sideelectrode 5 can be formed of a metal material such as, for example,silver, aluminum, copper, nickel, and palladium, out of which silver ispreferable. The light-receiving face-side electrode 5 can be formed by avapor deposition method, a printing and baking method with a pasteelectrode, a plating method, or the like, for example.

There will be no problem even if the order of the above-described steps(4), (5), (6) is changed.

(7) Step of Junction Isolation

Next, the junction isolation section 21 is formed in the separation band19 so as to have a circular shape as illustrated in FIG. 4 (g) tocomplete production of the photoelectric conversion element 10. Thejunction isolation section 21 can be formed by laser beam machining, forexample.

1-3. Photoelectric Conversion Element Assembly

A photoelectric conversion element assembly in accordance with the firstembodiment of the present invention will be described with reference toFIG. 5. FIG. 5 is a back view illustrating a configuration of thephotoelectric conversion element assembly in accordance with thisembodiment of the present invention, corresponding to the photoelectricconversion element shown in FIG. 1(b).

The photoelectric conversion element assembly of this embodimentincludes a first photoelectric conversion element 10 a and a secondphotoelectric conversion element 10 b. Each of the first and secondphotoelectric conversion elements 10 a, 10 b is the above-describedphotoelectric conversion element of first embodiment. The first and thesecond photoelectric conversion elements 10 a, 10 b are arranged so thatthe central axes 11 of each element are positioned on the same straightline, and the first electrode 2 of one photoelectric conversion elementand the second electrode 7 of the other photoelectric conversion elementare positioned on a straight line parallel to the central axes 11. Thefirst electrode 2 of one photoelectric conversion element and the secondelectrode 7 of the other photoelectric conversion element areelectrically connected by use of a linear inter-element wiring member17.

The first electrode 2 and the second electrode 7 are arrangedequidistantly apart from the central axis 11 both in the first andsecond photoelectric conversion elements 10 a, 10 b. Therefore, one ofthe first and second photoelectric conversion elements 10 a, 10 b isturned around an axis perpendicular to the principal surface by 180degrees, and then the central axes of the first and second photoelectricconversion elements 10 a, 10 b are arranged on the same straight line,the first electrode 2 of one photoelectric conversion element and thesecond electrode 7 of the other photoelectric conversion element willnecessarily be positioned on a straight line parallel to the centralaxes. Accordingly, the first electrode 2 of one photoelectric conversionelement and the second electrode 7 of the other photoelectric conversionelement can be electrically connected by use of the linear inter-elementwiring member 17. Since two photoelectric conversion elements can beconnected by use of the linear inter-element wiring member 17 accordingto this embodiment, the period of time for this wiring process can beshortened. In addition, the linear inter-element wiring member 17 isrelatively inexpensive, and therefore production costs can be reduced.

The shape and material of the inter-element wiring member 17 are notparticularly limited, and examples thereof include a rectangular copperwire having a surface plated with solder.

In addition, it is necessary to take a measure to prevent the secondelectrode 7 and the neighboring aluminum electrode 13 from beingshort-circuited by the inter-element wiring member 17. Examples of themeasure include: (1) a method in which the surface of the aluminumelectrode 13 is coated and insulated at least in a part where thealuminum electrode 13 contacts with the inter-element wiring member 17,and (2) a method in which the surface of the inter-element wiring member17 is coated and insulated in part. The method (1) provides an effect ofshortening of the period of time for the wiring process compared to theart disclosed in Non-Patent Document 2, because the second electrode 7and the inter-element wiring member 17 can be connected even in the caseof less accurate positioning of the second electrode 7 and theinter-element wiring member 17. In the method (1), it is preferable thatthe surface of the aluminum electrode 13 is further coated and insulatedso as to cover an area wider than the width, of the inter-element wiringmember 17 in terms of shortening of the period of time for the wiringprocess. The method of coating and insulating is not particularlylimited, and examples thereof include a method in which a resin paste isapplied by screen-printing.

In FIG. 5, the second electrode 7 of the first photoelectric conversionelement 10 a and the first electrode 2 of the second photoelectricconversion element 10 b are electrically connected by use of theinter-element wiring member 17. The first electrode 2 of the firstphotoelectric conversion element 10 a is electrically connected to thesecond electrode 7 of a third photoelectric conversion element arrangedat a side opposite to the side of the second photoelectric conversionelement 10 b (upper side of the first photoelectric conversion element10 a in FIG. 5). In addition, the second electrode 7 of the secondphotoelectric conversion element 10 b is electrically connected to thefirst electrode 2 of a fourth photoelectric conversion element arrangedat a side opposite to the side of the first photoelectric conversionelement 10 a (lower side of the second photoelectric conversion element10 b in FIG. 5). Thus, a photoelectric conversion element assembly inwhich three or more photoelectric conversion elements are electricallyconnected in series is obtained.

When four or more photoelectric conversion elements are arranged in amatrix to form a photoelectric conversion element assembly, all thephotoelectric conversion elements may be connected in series by use of abus bar for connecting the inter-element wiring members together in adirection perpendicular to the longer direction of the inter-elementwiring members.

4-1. Photoelectric Conversion Module

A photoelectric conversion module of the present invention has thefollowing configuration, for example.

A front cover such as a white plate glass and a filler made of atransparent resin such as EVA (ethylene-vinyl acetate copolymer) arearranged at the light-receiving side of the photoelectric conversionelement assembly, and a back side filler such as EVA and aweather-resistant film having a sandwich structure of, for example,insulator/metallic foil/insulator are arranged at the back side of thephotoelectric conversion element assembly. To the wiring members at theboth ends of the serial connection of the photoelectric conversionelement assembly, positive and negative lead wires are connected to takeout electric current via bus bars. The lead wires are arranged to reachthe back side of the weather-resistant film through through-holesprovided in the back side filler and the weather-resistant film.

The photoelectric conversion module of the present invention can beproduced as follows, for example.

The filler is arranged on the front cover, and thereon the photoelectricconversion element assembly is arranged with the light receiving surfacedown. The positive and negative lead wires are connected to the bus barsfor connecting the wiring members at the both ends of the serialconnection of the photoelectric conversion element assembly. The leadwires are got through the through-hole provided in the back side fillerto arrange the back side filler on the photoelectric conversion elementassembly. The lead wires are got through the through-hole provided inthe weather-resistant film to arrange the weather-resistant film on theback side filler. The filler is melt-solidified by pressurizing andheating this laminate by use of a vacuum laminator to obtain thephotoelectric conversion module.

2. Second Embodiment 2-1. Photoelectric Conversion Element

A configuration of a photoelectric conversion element of the secondembodiment of the present invention will be described with reference toFIGS. 6 (a) and 6 (b). FIGS. 6 (a) and 6 (b) are a plan view (figure ofa light-receiving surface) and a back view, respectively, illustratingthe configuration of the photoelectric conversion element of thisembodiment.

The photoelectric conversion element 10 of this embodiment is differentfrom that of the first embodiment mainly in that (1) the secondelectrode 7 has an asymmetry shape with respect to the center point ofthe penetrating-connecting section 9; (2) the distance between the firstelectrode 2 and the central axis 11, and the distance between thepenetrating-connecting section 9 and the central axis 11 are differentfrom each other; and (3) the base part 5 a of the light-receivingface-side electrode 5 has a wide part 5 c in a part to be connected tothe penetrating-connecting section 9. Other than that, the secondembodiment is basically the same as the first embodiment, and thedescription of the first embodiment is also true of this embodiment.

Effects to be produced by the above-described differences (1) and (2)will be described later. An effect to be produced by the above-describeddifference (3) is to enable reduction of the occupation area of thelight-receiving face-side electrode 5 while ensuring reliable connectionbetween the light-receiving face-side electrode 5 and thepenetrating-connecting section 9. The reduction of the occupation areaof the light-receiving face-side electrode 5 enables increase of thelight-receiving area.

2-2. Photoelectric Conversion Element Assembly

A photoelectric conversion element assembly of the second embodiment ofthe present invention will be described with reference to FIG. 7. FIG. 7is a back view illustrating a configuration of the photoelectricconversion element assembly of this embodiment, corresponding to thephotoelectric conversion element shown in FIG. 6(b).

The photoelectric conversion element assembly of this embodiment isdifferent from the photoelectric conversion element assembly of thefirst embodiment in that the first and second photoelectric conversionelements 10 a, 10 b are the above-described photoelectric conversionelements 10 a, 10 b of the second embodiment, respectively. Other thanthat, the second embodiment is basically the same as the firstembodiment, and the description of the first embodiment is also true ofthis embodiment.

In the photoelectric conversion element assembly of this embodiment, aswell, the first electrode 2 of one photoelectric conversion element andthe second electrode 7 of the other photoelectric conversion element canbe electrically connected by use of the linear inter-element wiringmember 17 as illustrated in FIG. 7.

In the first embodiment, the inter-element wiring member 17 overlapswith the penetrating-connecting section 9 as illustrated in FIG. 5, andthe penetrating-connecting section 9 is therefore under stress from theinter-element wiring member 17. In this embodiment, on the other hand,the distance between the first electrode 2 and the central axis 11, andthe distance between the penetrating-connecting section 9 and thecentral axis 11 are different from each other to allow the firstelectrode 2 and the penetrating-connecting section 9 to be arranged offa straight line parallel to the central axis 11, and the inter-elementwiring member 17 can be therefore arranged linearly in a part of thesecond electrode 7 so as to eliminate overlap with thepenetrating-connecting section 9. Accordingly, thepenetrating-connecting section 9 is prevented from being under stressfrom the inter-element wiring member 17.

In addition, as having an asymmetry shape with respect to the centerpoint of the penetrating-connecting section 9, the second electrode 7can be formed into a shape having a smaller area in the vicinity of thepenetrating-connecting section 9 and a larger area in a part contactingwith the inter-element wiring member 17 as illustrated in FIG. 7, forexample. Thereby, connection strength between the second electrode 7 andthe inter-element wiring member 17 can be increased.

3. Third Embodiment

A photoelectric conversion element assembly of the third embodiment ofthe present invention will be described with reference to FIG. 8. FIG. 8is a view illustrating a configuration of the photoelectric conversionelement assembly of this embodiment as seen from a back side of thephotoelectric conversion element.

The photoelectric conversion element assembly of this embodimentincludes a first photoelectric conversion element 10 a and a secondphotoelectric conversion element 10 b that are different from each otherin electrode arrangement, and the first electrode 2 of the firstphotoelectric conversion element 10 a and the second electrode 7 of thesecond photoelectric conversion element 10 b are connected by use of thelinear inter-element wiring member 17. The first photoelectricconversion element 10 a and the second photoelectric conversion element10 b used for this embodiment have a configuration in which the firstelectrode 2 and the second electrode 7 are arranged linearly in elementsadjacent to each other. As for the arrangement of the first electrode 2and the second electrode 7 within each photoelectric conversion element,it is desirable that the first electrode 2 or the second electrode 7 isarranged on the central line of the element, and the first electrode 2and the second electrode 7 are arranged at symmetric positions withrespect to the central line.

Though this embodiment needs to use two kinds of photoelectricconversion elements, electrode position, that is, wire position of thephotoelectric conversion element can be designed with more variancecompared with the first embodiment and the second embodiment. Inaddition, the arrangement of the first electrode 2 and the secondelectrode 7 at symmetric positions with respect to the central line ofthe element is advantageous in that the amount of electric current thatflows into the inter-element wiring member 17 is even and wiring loadcan be designed readily in this case.

The various characteristics shown in the above-described embodiments maybe combined with one another. For example, the shape of thelight-receiving face-side electrode in the first embodiment and theshape of the second electrode in the second embodiment may be combinedto be included in one photoelectric conversion element. When oneembodiment includes a plurality of characteristics, one, or two or moreof the characteristics may be appropriately selected to be applied tothe present invention independently or in combination.

1. A photoelectric conversion element assembly, comprising: a firstphotoelectric conversion element; and a second photoelectric conversionelement, each of which comprises: a first semiconductor layer of a firstconductivity type; a first electrode arranged on a back side of thefirst semiconductor layer and electrically connected to the firstsemiconductor layer; a second semiconductor layer of a secondconductivity type, the second semiconductor layer brought into contactwith the first semiconductor layer and arranged at least in part on alight-receiving side of the first semiconductor layer; a light-receivingface-side electrode provided so as to be electrically connected to thesecond semiconductor layer on its light-receiving side; a secondelectrode arranged on the back side of the first semiconductor layer,and electrically separated from the first semiconductor layer, butelectrically connected to the second semiconductor layer; and apenetrating-connecting section penetrating the first semiconductorlayer, and electrically separated from the first semiconductor layer,but electrically connecting the light-receiving face-side electrode withthe second electrode, wherein the first electrode of one photoelectricconversion element and the second electrode of an other photoelectricconversion element are electrically connected by use of a linearinter-element wiring member.
 2. The assembly according to claim 1,wherein the second electrode has an asymmetrical shape with respect to acenter point of the penetrating-connecting section.
 3. The assemblyaccording to claim 1, wherein a distance between the first electrode andthe central axis, and a distance between the penetrating-connectingsection and the central axis are different from each other in eachphotoelectric conversion element.
 4. A photoelectric conversion modulecomprising the photoelectric conversion element assembly according toclaim 1.